A recent study published in the journal Proceedings of the National Academy of Sciences It revealed a historical discovery about the ancient history of humanity. According to researchers, about 900 thousand years ago, a mass migration of early humans from Africa occurred, at the same time that the population of our ancestors decreased dramatically to only about 1,300 individuals.
This discovery not only confirms previous genomic studies chronicling population declines, but also suggests a direct link to an event known as the Middle Pleistocene transition. During this period, the Earth's climate was severely disturbed, leading to the extinction of many species.
The early migration of humans from Africa and across Europe and Asia is a difficult topic to fully understand. The available evidence consists mainly of bone records and stone artefacts, which can be difficult, if not impossible, to date. However, recent studies indicate that this migration was not an isolated event, but rather a series of movements undertaken by human groups in search of new environments.
Two previous studies have linked human migration and population collapse, using different analysis methods. A detailed analysis of the human genome has found evidence of a loss of genetic diversity about 900,000 years ago. Another study, which examined archaeological sites in Eurasia, dated the population collapse to 1.1 million years ago.
This difference prompted geologists Giovanni Mutoni of the University of Milan and Dennis Kent of Columbia University to conduct an investigation to more precisely determine the timing of the population collapse. Experts have reevaluated records of human habitation points in Eurasia and identified a group of archaeological sites, reliably dating back to 900,000 years ago.
They were compared to marine sediment records, which provide evidence of climate change over time. This combined analysis suggests that the population collapse and mass migration occurred simultaneously.
During the middle Pleistocene transition, global ocean levels declined and Africa and Asia became drier. Harsh conditions forced humans living in Africa to search for new lands to survive. As sea levels fell, land routes to Eurasia opened up, allowing these groups to migrate to new areas.
Researchers stress that this mass migration does not mean that humans did not migrate previously. Instead, it was an important event that coincided with the population collapse and was driven by climate change that occurred 900,000 years ago.
“We propose that increased aridity during marine isotope phase 22, which caused the spread of savannas and arid regions across much of the African continent, forced the first populations of Homo in Africa to adapt or migrate to avoid extinction,” the researchers wrote in the article.
“Rapid migration in response to an extreme climatic stimulus and its associated means of escape are what may explain (…) the migration out of Africa 0.9 million years ago and contribute to the genomic evidence of contemporary African ‘bottleneck’ populations.” Experts.
